It is necessary for a projector to correct distortion of projected images for appropriate image display. For example, as disclosed in Japanese Patent Publication No. JP-A-2003-29714, a projector may perform distortion correction calculation using image information of input images. As an origin for the distortion correction calculation, for easy calculation, the midpoint of the lower side of a display area (liquid crystal panel) or the point at the upper left of the display area is used as disclosed in Japanese Patent Publication No. JP-A-2003-29714.
However, when the midpoint of the lower side of the display area is used as the origin, the distances to the upper left and the upper right of the image after distortion correction become longer, and, when the point at the upper left of the display area is used, the distance to the lower right of the image after distortion correction becomes longer. The longer the distance from the origin, the further an error of distortion correction calculation increases. On this account, when an image having a laterally symmetric pattern, an image having a vertically symmetric pattern, an image with moire, or the like is projected using these methods, part of the patterns and moire are observed in a distorted condition.